1. Field of the Invention
Devices, systems, and methods for warming intravenous (IV) fluids are disclosed and, more particularly, devices, systems, and methods for warming IV fluids using a single power pack and controller to control the duty-cycle of more than one fluid warming unit are disclosed.
2. Description of the Related Art
When introducing fluids into the human body, e.g., intravenously, it is desirable to maintain the fluids at a temperature at or near normal body temperature. Introduction of fluids into the human body at lower temperatures may induce shock or hypothermia and can lengthen the healing process. As a result, devices have been developed to warm fluids prior to their infusion into the human body.
For example, in pending U.S. patent application Ser. No. 10/876,824 to David E. Cassidy entitled Medical Fluid Warming System, which was publishes as Publication Number 2005/008354 and which is incorporated in its entirety herein by reference, inline fluid warmers have been developed to warm fluid in the delivery line between the fluid source, i.e., the intravenous drip bag (IV), and the point of infusion. More specifically, fluid warmers have been developed to warm fluid in the delivery line itself as the fluid passes through the delivery line or, alternatively, fluid warmers have been developed to warm fluid as the fluid passes through the fluid warmer.
In the case of the latter, fluid to be infused into a human body follows a serpentine path through a heat exchanger that warms the fluid to a desired temperature. Temperature sensors at the input and output of the warming device provide fluid temperature data to a controller, e.g., a proportional-integral-derivative (PID) controller. The PID controller provides signals to control the switching ON and OFF of a gate(s). The state of the gate signal controls whether power from a power source is applied or withheld from the heat exchanger.
Because the gates are binary, they are either ON or OFF. When OFF, the power source is idle, awaiting fluid temperature data that will cause it to open the gate.
Slender poles on wheels or casters are used in medical facilities to support and/or transport one or more IVs and related, mounted ancillary equipment, e.g., fluid warming units to warm the fluid in the IVs, pumps to control the flow of the fluid into a patient, power sources, and the like. Necessarily, to provide sufficient head for the IV drip, IVs are placed uppermost on the poles, which produces a high center of gravity and imbalance. When multiple IVs are placed on a single pole, the instability is further exacerbated and may lead to overturning or tipping, which may cause injury or damage equipment.
To lower the center of gravity of the pole, related ancillary equipment, generally, can be mounted on the pole and arranged to distribute the weight of the ancillary equipment over more of the IV pole. However, the available space on a pole is still limited. Therefore, the avoidance of redundancy of ancillary equipment is desirable.
Conventionally, if a patient requires multiple IV drips that contain and deliver different medicines or fluids, because each of the different fluids may require delivery at a different rate, a fluid warming unit is dedicated to each IV to control the fluid infusion temperature. Because each fluid warming unit is provided with a unique power source, e.g., a power pack, it would be desirable to provide devices, systems, and methods to reduce the number and weight of redundant power sources by delivering power from a single power source to more than one IV fluid warming unit.
Specifically, it would be desirable to provide devices, systems, and methods that control a single power pack to operate more than one IV fluid warming unit and a controller that uses duty-cycle to control the timing of power flowing to each fluid warming unit.
More specifically, it would be desirable to provide devices, systems, and methods that sense IV fluid temperature levels; that signal fluid temperature data to the controller; and, based on fluid temperature data, that adjust the duty-cycle, e.g., by pulse width modulation (PWM), of each of the IV fluid warming units, and that, further, apportion the IV fluid warming unit duty-cycles over the work cycle of the device.
Furthermore, the location of multiple IVs, fluid warming units, and associated delivery lines on a single pole can produce a jumbled or tangled appearance, making association of a particular delivery line with its respective warming unit and/or IV difficult. Applying higher temperatures to the wrong fluids, however, could lead to serious injury.
Conventionally, colored bands have been placed on the tubing of the delivery lines. However, association of the color-tagged delivery line with its respective warming unit and/or IV is still difficult. Accordingly, it would also be desirable to provide devices, systems and methods that facilitate association of signal and/or data transmission lines that in operational association with a power pack with a particular fluid warming unit.